From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-9.6 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id E9F35C4742C for ; Thu, 5 Nov 2020 13:05:02 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 82C6620735 for ; Thu, 5 Nov 2020 13:05:02 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="pO6y9W7Y" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730429AbgKENFB (ORCPT ); Thu, 5 Nov 2020 08:05:01 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59452 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729992AbgKENFA (ORCPT ); Thu, 5 Nov 2020 08:05:00 -0500 Received: from mail-il1-x142.google.com (mail-il1-x142.google.com [IPv6:2607:f8b0:4864:20::142]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 73451C0613CF; Thu, 5 Nov 2020 05:04:59 -0800 (PST) Received: by mail-il1-x142.google.com with SMTP id y17so1304921ilg.4; Thu, 05 Nov 2020 05:04:59 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=JZXQ3BAddNN3gYrfwjUK8hjD6WjwUEDBLj1eNYEOzUo=; b=pO6y9W7YRw3qCKIWJKv7KZ5gPH5HAp3M0yP7f3VXh/iCV2RltcdOM+NZMmK+Lr6WAG bJAR8Py8WsSCI0QAyk+8oFNjw/b8qmB44FFdIACEWpcu2gvFaflNUqgOmr1dAYQ5WzUL JKhlX0+EzqmRcvtWgitpsmPUMsatZVa+9VJiF22i786f4JmuJM0zkGNME1HKOzSK/aRu BQnPNvMGhSGbSPtpMYXm1M1u2Cw9YF2pKiVAPxZxDbbf91KXXtLR13ClcVPE0zPWSByk f10H23ydhFYmul63BdYVywg3N1sGTA7+tsmqNguEutZ9RsJsBRw701fvMoeJOwJx0lC+ wMoQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=JZXQ3BAddNN3gYrfwjUK8hjD6WjwUEDBLj1eNYEOzUo=; b=TJNCnIUYMo7I3IAYbaN3OeebjG0neukjAW+q61WmZ5LugmKNffWshztCcTT9mWSTHD kM7ylbnJdH3t2oM5t8mP//pIk2ST0G1Sc/z1y7J0pf4OqcB2wuEdE/Tidoz0dUXpyrSW epReaAQl5hekmC+cbI3KtDL3ctM7C9oFMqToeGgiMFul3rxCuNhdXo4kjT1rRt3DcBq8 dFG/4CzPA1/XJEMfW+fsnyy+4Hp9j2ZsG2Nz+8e3L+I/dxEk5kX1ohmz+vv/RhnUSZaQ 8x+EOWiyExWG4UpA/OJ/Epc/o3t3EKH08ImpLhuAwE/cuvWS1U4Mlge7nLpmDEl52tAv vvag== X-Gm-Message-State: AOAM533pXas4P36JugDaodvU2cP17fDnBhh9PcBygN3zOmZTSDI/MjDo m/wZw14CLjJvh23km5VoD+ESRcHoV9wUtKcp9MQ= X-Google-Smtp-Source: ABdhPJxDmC0wfjLJrqd5m/AlPqEkfeGyCmP9jd4qeKTe5TycmK1XIO774yC4d5EC1LAMCmHsJzoFb5yFBg6q19YBHMo= X-Received: by 2002:a92:3003:: with SMTP id x3mr1690953ile.93.1604581498765; Thu, 05 Nov 2020 05:04:58 -0800 (PST) MIME-Version: 1.0 References: <20201103131754.94949-1-laoar.shao@gmail.com> <20201103131754.94949-2-laoar.shao@gmail.com> <20201103194819.GM7123@magnolia> <20201104162640.GD7115@magnolia> In-Reply-To: <20201104162640.GD7115@magnolia> From: Yafang Shao Date: Thu, 5 Nov 2020 21:04:22 +0800 Message-ID: Subject: Re: [PATCH v8 resend 1/2] mm: Add become_kswapd and restore_kswapd To: "Darrick J. Wong" Cc: Andrew Morton , Dave Chinner , Christoph Hellwig , Matthew Wilcox , Michal Hocko , Linux MM , linux-fsdevel@vger.kernel.org, linux-xfs@vger.kernel.org Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On Thu, Nov 5, 2020 at 12:26 AM Darrick J. Wong wrote: > > On Wed, Nov 04, 2020 at 10:17:16PM +0800, Yafang Shao wrote: > > On Wed, Nov 4, 2020 at 3:48 AM Darrick J. Wong wrote: > > > > > > On Tue, Nov 03, 2020 at 09:17:53PM +0800, Yafang Shao wrote: > > > > From: "Matthew Wilcox (Oracle)" > > > > > > > > Since XFS needs to pretend to be kswapd in some of its worker threads, > > > > create methods to save & restore kswapd state. Don't bother restoring > > > > kswapd state in kswapd -- the only time we reach this code is when we're > > > > exiting and the task_struct is about to be destroyed anyway. > > > > > > > > Cc: Dave Chinner > > > > Acked-by: Michal Hocko > > > > Reviewed-by: Darrick J. Wong > > > > Reviewed-by: Christoph Hellwig > > > > Signed-off-by: Matthew Wilcox (Oracle) > > > > Signed-off-by: Yafang Shao > > > > --- > > > > fs/xfs/libxfs/xfs_btree.c | 14 ++++++++------ > > > > include/linux/sched/mm.h | 23 +++++++++++++++++++++++ > > > > mm/vmscan.c | 16 +--------------- > > > > 3 files changed, 32 insertions(+), 21 deletions(-) > > > > > > > > diff --git a/fs/xfs/libxfs/xfs_btree.c b/fs/xfs/libxfs/xfs_btree.c > > > > index 2d25bab..a04a442 100644 > > > > --- a/fs/xfs/libxfs/xfs_btree.c > > > > +++ b/fs/xfs/libxfs/xfs_btree.c > > > > @@ -2813,8 +2813,9 @@ struct xfs_btree_split_args { > > > > { > > > > struct xfs_btree_split_args *args = container_of(work, > > > > struct xfs_btree_split_args, work); > > > > + bool is_kswapd = args->kswapd; > > > > unsigned long pflags; > > > > - unsigned long new_pflags = PF_MEMALLOC_NOFS; > > > > + int memalloc_nofs; > > > > > > > > /* > > > > * we are in a transaction context here, but may also be doing work > > > > @@ -2822,16 +2823,17 @@ struct xfs_btree_split_args { > > > > * temporarily to ensure that we don't block waiting for memory reclaim > > > > * in any way. > > > > */ > > > > - if (args->kswapd) > > > > - new_pflags |= PF_MEMALLOC | PF_SWAPWRITE | PF_KSWAPD; > > > > - > > > > - current_set_flags_nested(&pflags, new_pflags); > > > > + if (is_kswapd) > > > > + pflags = become_kswapd(); > > > > + memalloc_nofs = memalloc_nofs_save(); > > > > > > > > args->result = __xfs_btree_split(args->cur, args->level, args->ptrp, > > > > args->key, args->curp, args->stat); > > > > complete(args->done); > > > > > > > > - current_restore_flags_nested(&pflags, new_pflags); > > > > + memalloc_nofs_restore(memalloc_nofs); > > > > + if (is_kswapd) > > > > + restore_kswapd(pflags); > > > > > > Note that there's a trivial merge conflict with the mrlock_t removal > > > series. I'll carry the fix in the tree, assuming that everything > > > passes. > > > > > > > This patchset is based on Andrew's tree currently. > > Seems I should rebase this patchset on your tree instead of Andrew's tree ? > > That depends on whether or not you want me to push these two patches > through the xfs tree or if they're going through Andrew (Morton?)'s > quiltset. > > Frankly I'd rather take them via xfs since most of the diff is xfs... > Sure, I will rebase in on the xfs tree. > > > > > > > } > > > > > > > > /* > > > > diff --git a/include/linux/sched/mm.h b/include/linux/sched/mm.h > > > > index d5ece7a..2faf03e 100644 > > > > --- a/include/linux/sched/mm.h > > > > +++ b/include/linux/sched/mm.h > > > > @@ -278,6 +278,29 @@ static inline void memalloc_nocma_restore(unsigned int flags) > > > > } > > > > #endif > > > > > > > > +/* > > > > + * Tell the memory management code that this thread is working on behalf > > > > + * of background memory reclaim (like kswapd). That means that it will > > > > + * get access to memory reserves should it need to allocate memory in > > > > + * order to make forward progress. With this great power comes great > > > > + * responsibility to not exhaust those reserves. > > > > + */ > > > > +#define KSWAPD_PF_FLAGS (PF_MEMALLOC | PF_SWAPWRITE | PF_KSWAPD) > > > > + > > > > +static inline unsigned long become_kswapd(void) > > > > +{ > > > > + unsigned long flags = current->flags & KSWAPD_PF_FLAGS; > > > > + > > > > + current->flags |= KSWAPD_PF_FLAGS; > > > > + > > > > + return flags; > > > > +} > > > > + > > > > +static inline void restore_kswapd(unsigned long flags) > > > > +{ > > > > + current->flags &= ~(flags ^ KSWAPD_PF_FLAGS); > > > > +} > > > > + > > > > #ifdef CONFIG_MEMCG > > > > DECLARE_PER_CPU(struct mem_cgroup *, int_active_memcg); > > > > /** > > > > diff --git a/mm/vmscan.c b/mm/vmscan.c > > > > index 1b8f0e0..77bc1dd 100644 > > > > --- a/mm/vmscan.c > > > > +++ b/mm/vmscan.c > > > > @@ -3869,19 +3869,7 @@ static int kswapd(void *p) > > > > if (!cpumask_empty(cpumask)) > > > > set_cpus_allowed_ptr(tsk, cpumask); > > > > > > > > - /* > > > > - * Tell the memory management that we're a "memory allocator", > > > > - * and that if we need more memory we should get access to it > > > > - * regardless (see "__alloc_pages()"). "kswapd" should > > > > - * never get caught in the normal page freeing logic. > > > > - * > > > > - * (Kswapd normally doesn't need memory anyway, but sometimes > > > > - * you need a small amount of memory in order to be able to > > > > - * page out something else, and this flag essentially protects > > > > - * us from recursively trying to free more memory as we're > > > > - * trying to free the first piece of memory in the first place). > > > > - */ > > > > - tsk->flags |= PF_MEMALLOC | PF_SWAPWRITE | PF_KSWAPD; > > > > + become_kswapd(); > > > > set_freezable(); > > > > > > > > WRITE_ONCE(pgdat->kswapd_order, 0); > > > > @@ -3931,8 +3919,6 @@ static int kswapd(void *p) > > > > goto kswapd_try_sleep; > > > > } > > > > > > > > - tsk->flags &= ~(PF_MEMALLOC | PF_SWAPWRITE | PF_KSWAPD); > > > > - > > > > return 0; > > > > } > > > > > > > > -- > > > > 1.8.3.1 > > > > > > > > > > > > -- > > Thanks > > Yafang -- Thanks Yafang